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Flexor Tendon Injuries
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Flexor Tendon Injuries
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Language: EN.
Segment:0 .
HASHAM AWAN: This talk is Flexor Tendon Injuries. I'm Hisham Awan from the Ohio State University. So we're going to talk about the anatomy and vascularity of flexor tendons, the classification biology of tendon healing.
HASHAM AWAN: We'll talk about some repair techniques, post operative rehab, outcomes, complications as well as briefly, talk about flexor tendon reconstruction. So flexor tendon injuries are traumatic injuries classified by different zones. The location of the injury directly affects the healing potential as there are different anatomical considerations depending on the zone of injury.
HASHAM AWAN: Of zone two injuries, which are within the superflexor tendon sheath, which were previously called injuries in no man's land once had dismal results, but modern repair methods and rehab protocols have significantly improved outcomes and techniques. So we'll start with the anatomy. The flexor digitorum superficialis muscle originates from the medial epicondyle as well as the ulnar collateral ligament of the elbow and coronoid process.
HASHAM AWAN: There's a radial head that starts at the radial shaft, just distal to the bicipital tuberosity, and these become tendinous at the distal forearm and insert onto the polymer metaphysis of the middle phalanx of the index middle ring and small fingers. On the small finger, this can be pretty variable and pretty diminutive or absent in certain populations. The origin of the flexor
HASHAM AWAN: digitorum profundus tendon is a muscle belly is on the proximal ulna and interosseous membrane. The insertion is on the palmar base of the distal phalanx of the index middle ring and small fingers. The FPL is also a consideration. It originates from the diaphyseal radius and the adjacent interosseous membrane and inserts on the palmar base of the distal phalanx of the thumb.
HASHAM AWAN: Also important to note, it is the most radial structure in the carpal tunnel. And here's a cross sectional anatomy of the flexor tendons seen in the carpal tunnel with the FPL here, this most radial tendon, the FCR is outside the carpal tunnel here. Here are the remainder of the tendons in the carpal tunnel, FDS and FDP tendons.
HASHAM AWAN: The anatomy of the flexor tendon sheath is also important. Most important are the A2 and A4 pulleys, which we try and preserve as much as we can although later studies have shown that you can strategically vent the pulleys in order to optimize outcomes with repair and we'll get to that a little bit later when we talk about surgical techniques.
HASHAM AWAN: Here's the anatomy of the sheath with the addition of the vasculatures so the digital arteries run along the side and there are transverse branches of the digital arteries that provide, excuse me, provide blood supply to the tendon. These vincula also are the terminal continuations of the digital arteries and are important in the blood supply of the tendons.
HASHAM AWAN: Campers Kiazim [?] is the location where the FDS splits so this is where the FTP runs between the two slips of the FTP tendons. The flexor tendon sheath of the thumb is a little bit different than the fingers. The most important pulley to preserve is this oblique pulley. Anatomical studies have shown different variations of this
HASHAM AWAN: a variable pulley. Sometimes there's a separation between the A1 and the A variables. Sometimes they're directly contiguous and sometimes it takes more of an oblique course so just be aware of the variations of the flexor sheath of the thumb. But again, the most important pulley to preserve is the oblique pulley.
HASHAM AWAN: Flexor tendon excursion, so the numbers here on this slide indicate the millimeter of tendon excursion at the site as the digit moves from neutral extension to full flexion. So the vascular supply, the tendons receive nutrition from both synovial which is through diffusion as well as direct blood flow from the digital arteries
HASHAM AWAN: so the transverse branches again terminate into the vincula and that's where the blood supply also enters the tendon and seen here in a cross section, they enter on the dorsal side so there's a relatively avascular area on the volar aspect of the tendon. So here are the zones as described by Kleinert. So Zone 1 is distal to the FDS insertion. Zone 2 was no man's land.
HASHAM AWAN: These are where the FDS and FTP tendons travel through the flexor tendon sheath. Zone 3 is more proximal and this is the lumbrical origin. Zone 4 is within the carpal tunnel and Zone 5 is proximal to the carpal tunnel. The thumb zones are a little bit different. Zone 1 is around the level of the IP join.t Zone 2 is within the superflexor tendon sheath, and Zone 3 is proximal to that.
HASHAM AWAN: So next, we're going to talk a little bit about the biology of tendon healing. So first, we'll talk about the structure of the actual tendon. So tendon is made up of type 1 collagen, which is organized into fibrils. The fibrils form fascicles within the endotenon, and then the fascicles and endotenon are encircled by epitenon and that forms the overall structure of the tendon. There's different phases of tendon healing.
HASHAM AWAN: There's the early inflammatory phase, which was within the first 5 to 7 days from injury. Here, there's cellular proliferation in the fibroblastic or proliferative phase, which goes from about week one up to about a month after injury. There's fibroblast proliferation and here we have disorganized collagen, usually type III collagen, and then the remodeling phase, which is after 28 days, there is reorganization of the collagen.
HASHAM AWAN: So here we have a picture of the tendon and see what's going on cellularly. On the top left, this is the early inflammatory phase within one week of the tendon healing. The top right now we're starting to get some fibroblast proliferation and collagen formation, but it's disorganized. And finally in the remodeling phase, the collagen is organized and remodeled, more in line with the tendon.
HASHAM AWAN: Also important to see here is we have some adhesions indicating some extrinsic healing of the tendon. So we talk about intrinsic and extrinsic healing. So intrinsic is within the epitenon, extrinsic is from the synovial sheath. So Gelderman and colleagues noted that immobilized canine flexor tendons healed by ingrowth of cells from the flexor tendon sheath, whereas once the tendons were mobilized with range of motion, the tendons healed, tendons healed by cells from the tendon itself
HASHAM AWAN: so when mobilized, there was more intrinsic healing. When immobilized there was extrinsic healing. So a rehab after flexor tendon surgery is a balancing act between intrinsic and extrinsic healing. We're trying to minimize the amount of extrinsic healing to prevent adhesions and to allow for the tendon to glide smoothly within the sheath.
HASHAM AWAN: So evaluation of these injuries includes a thorough physical exam. So you'll note a resting posture with the finger extended. You can also do a tenodesis where you flex and extend the wrist and see if the tendon is intact. It should flex once the wrist is extended. A good neurovascular exam is also very important. If there is vascular compromise these are more of an emergent nature to these injuries, whereas if there is not, then these can be sent out and fixed electively.
HASHAM AWAN: So timing, ideally, you'd like to fix these within a week. If you wait more than a week or two or three, there's more retraction and scarring and so that makes the repair more technically difficult as well as retraction. To a certain extent will prevent you from getting the tenant out to length and would require grafting.
HASHAM AWAN: So you try and fix these as soon as possible within a reasonable time frame. So first we're going to talk about Zone 1 injuries, which are Jersey fingers, which are FTP avulsions from the middle phalanx. So Zone 1 injuries were classified by Leddy and Packer. And in these, in this classification, type one has the most retraction. So type one, the tendon is retracted into the palm with disruption of the Vincula system, which is disrupted completely.
HASHAM AWAN: These ones you really should fix as soon as possible. If more than a week or two, it's really hard to get these out to length because of scarring. Type two injuries is where the FTP retracts to the level of the PIP joint. Here the vinculum longest, the profundus is still intact, providing some blood supply and preventing the tendon from retracting any further. Type three injuries have a large bony fracture fragment, which gets caught up on the A4 pulley, which prevents the tendon from retracting.
HASHAM AWAN: When you get to a type 4 injury, there's a large avulsion fracture, but the tendon also pulls off of the fragment and is frequently retracted all the way to the palm. Again, these should be fixed as soon as possible. These are called double avulsions because of the avulsion fracture off of the remainder of the distal phalanx. And the tendon also avulses off of the fracture fragment.
HASHAM AWAN: Finally, the type 5 injury is the same as the type four, except for there's also additional fracture of the remaining distal phalanx. There's different repair techniques that can be done in Zone 1. Pull out suture is a common way, these are fixed, these risk nail deformities because you're passing sutures out through the nail.
HASHAM AWAN: You try and go distal to the germinal matrix to try and prevent this complication. Suture anchors are nice because they're all inside, so you don't have to worry about nail compromise. And then finally, these are a hybrid technique which has been shown to be the strongest technique where you have a suture anchor in addition to a pull out suture. So here's an example of a Zone 1 case example. This is a type 4 injury.
HASHAM AWAN: So you see the large bony fragment in addition to tendon avulsion all the way down to the palm. This was fixed with a plate as well as sutures, which were tied around the screw as opposed. Zone Rangers. You have to be careful not to over tighten the FTP repair so if it's really tight, if you've repaired in too much flexion, then you can
HASHAM AWAN: get what's called a Quadriga effect. So overtightening one of the tendons prevents full flexion of the remainder of the tendons. So next, we'll move on to Zone 2 injuries, which are the most common zone of injury. These also have the most variable result. These are within the flexor tendon sheath so these are prone to adhesions but again, newer repair and rehab techniques have improved outcomes.
HASHAM AWAN: So the goal is in Zone two, you want to prevent gap formation, which can lead to re-rupture. You want to try and prevent adhesions, which could lead to stiffness and loss of active range of motion. You want to allow differential gliding between the FDS and FTP tendons, you want to allow gliding under the pulleys and you want to perform a repair of adequate strength to allow for early rehab.
HASHAM AWAN: So there's several considerations with Zone 2 injuries, so timing, type of anesthesia, approach, retrieval of the tendon, management of the pulleys, core suture, epi tendinous suture and rehab. So timing, again, these are not emergent unless there is vascular compromise so we typically fix these as soon as possible to try to minimize retraction and scarring.
HASHAM AWAN: So this is a great article from Don Lalande who's done a lot of great work with wide awake surgery, particularly flexor tendon repair, with the patient being wide awake. This is from hand clinics in 2013. So you inject 1% lidocaine with epinephrine buffered with sodium bicarb. You allow 25 minutes for maximal vasoconstriction. This surgery can also be done under a if the patient is not really up for wide awake anesthesia, it can be done under a local with sedation or a regional block.
HASHAM AWAN: Rarely would you need a general anesthetic for this. So this slide looks at how to inject anesthesia for a flexor tendon repair under a wide awake anesthesia. We usually use a 9 to 1 or 8 to 2 ratio of 1% lidocaine with epinephrine buffered with sodium bicarb. You start in the palm. If this is a Zone 2 injury, you start in the palm and inject a few cc's around the digital bundles and then you inject about a cc along each segment where you're going to have dissection to try and minimize bleeding.
HASHAM AWAN: And this works really well, there's really minimal pain with this type of local infiltration and it's pretty well tolerated. So here's the surgical approaches with types of incisions you can use. My preference is the mid lateral approach here. The reason for that is there's not an incision over the top of the tendons where if it breaks down, you have a wound right over the top of the repair you just performed.
HASHAM AWAN: So I prefer the mid lateral approach outlined in the middle picture here and you can burr it right in the palm. Here's an example of an incision for a thumb flexor tendon laceration. So sometimes it can be tricky to retrieve the tendon as they do retract, sometimes they curl back on themselves.
HASHAM AWAN: So some things you can do, you can selectively open up the sheath, you can find the tendon. If it's retracted, you can find it proximal to the A1 pulley and use. In the middle picture, this is a pediatric feeding tube you can use to tunnel the tendon through to the distal stump. This picture on the right is what's called a suture shuttle. It's made by Arthrex. I have no conflict there, but basically it's like a finger trap for the tendon
HASHAM AWAN: and then this you can pass this through the flexor tendon sheath. There's also a device that's sort of like a that acts like a shoehorn. So here, this clear plastic device is acting like a shoehorn to allow the tendon to be passed through the flexor tendon sheath and retrieve distally.
HASHAM AWAN: Here's a another example of, another view of that tendon passed through the sheath. So setting up the repair, some technical points. Once you have the tendon passed. So pulley management. This is an article by Jim Boateng looking at their experience at 300 tendons.
HASHAM AWAN: So we were previously always told to preserve A2 and A4. More recent literature indicates that you can sacrifice all of A4 if it allows for ease of repair and also, it would still allow the tendon to glide. This article looks at ways you can vent the pulleys strategically in a location that allows for the ease of repair as well as tendon gliding. So their hypothesis was it's not as important, which pulleys.
HASHAM AWAN: What was more important is the size of the opening in the flexor tendon sheath. Obviously still A2 pulley is the most important, but you can sacrifice some of it if it enhances your repair as long as the repair does not impinge on the flexor sheath. So here's a schematic from their article where the, the level of the tendon laceration was identified, then this looks at the amount of sheath pulley you can release so that you are looking at the ends of the tendon for a direct repair and then you can test the repair with active and passive range of motion
HASHAM AWAN: so that you know that the repair is not catching on the edges of your pulleys and you can selectively vent the pulleys if needed if there is impingement with the repair. The next consideration is the core suture. So again, the most important factor is the number of strands that cross the repair site so there's a balance.
HASHAM AWAN: You want to have a strong repair, but you also don't want it to get too crowded and have too many sutures because it can be more technically demanding the number of sutures that you have across loop sutures allow for two strands per pass. So you can create two strands, but just by one pass of your needle. So a lot of people like to use loop sutures when fixing flexor tendons.
HASHAM AWAN: Also, you want to have a minimum of four strands, which would be strong enough to allow for early motion and you want to try and shoot for about a centimeter from the end of the tendon with your bite of your core sutures. And here's an example of a loop suture seen in the bottom right. Now, here's an example of several different types of core sutures. There's many different core sutures.
HASHAM AWAN: A lot of them work, work well and work just fine, but again, it really should be whatever you're most comfortable with, ideally at least a minimum of four strands, if not more. My preference is the six strand repair on the bottom left, the M-Tang repair. And again, when you do this repair, you don't want it to have a gap. You want it to have no tension.
HASHAM AWAN: You want it to have a little bit of tension and a little bit of bunching is OK because it's more resistant to gapping, more resistant to rupture. The epi-tendinous suture is also important for a couple of different reasons, so it can both enhance the repair strength by up to 50%. Now usually we quote around 20%, but some studies show up to 50% increase in the repair site.
HASHAM AWAN: It's not truly an epi tendinous, it's usually taking a thicker bite of the tendon with your epi tendinous stitch. It also tidies up the repair site, so if there are some rough edges after your core sutures, then you can tuck these in with the epi tendinous stitch. Now these are usually done with a 5-0 or 6-0 monofilament suture. I use a 5-0 prolene for my epi tendinous repairs. The digital flexion extension test can be done after the repair
HASHAM AWAN: so there's three parts. You first check passive full extension to see if there's to make sure there's no gapping. Next, you want to do flexion with moderate flexion to make sure there's smooth gliding within the sheath, and then you want to fully check in full flexion to make sure there's no impingement on the sheath. So here's a video courtesy of Don Lalonde.
HASHAM AWAN: And where active motion is used to check the repair. So we we're checking to see if there's impingement on the sheath and there was some impingement on the distal part of the repair. So the pulley was vented a little bit more using the scissors there to open up what looks like the A4 pulley this video.
HASHAM AWAN: So again, my preference for Zone 2 flexor tendon repairs. I do a wide awake whenever the patient is up for it. Some patients are not too thrilled about the idea of staying awake for the surgery, but most of them, once you discuss with them and educate them, are pretty reasonable about it.
HASHAM AWAN: And the nice thing about doing it awake is that you can also educate the patient while they're having surgery. So you can talk about the long road of rehab that they have in front of them. So I do a six strand repair using a looped fiber wire suture and then a 5-0 epi tendonous running stitch and then early active protocol in the right patient. So here's an example of a six strand repair.
HASHAM AWAN: The FTP tendon is seen completely lacerated. The FDS was partially lacerated here. Here is a needle being used to hold the ends of the tendon in place. And this is the six strand repair on the left. And then finally, the epigenetics running suture was placed afterwards. And here's a video depiction of that courtesy of Jim Boateng and plastic reconstructive surgery.
HASHAM AWAN: So you first make the first u and lock the suture then you pass the first longitudinal limb. You pass this across the tendon.
HASHAM AWAN: This is the transverse part of the suture. You be careful with the neurovascular bundles when you're doing that. Then you take. Suture the needle back through. And then back on the
HASHAM AWAN: proximal stump of the tendon. Then completing the u repair. These are tied and cut, and then the longitudinal limb and the center is then placed. Again, you want to shoot for about a centimeter on the U part and then about a centimeter and a quarter on this one. This is passing the center.
HASHAM AWAN: This is completing this sixth strand and then here's the peripheral upper tendinous stitch. And that opened up the sheath so that the tendon would glide more smoothly. Here's a case example of mine. Here's a 17-year-old male who presented with a laceration to his middle ring and small fingers, four months prior was told everything was fine.
HASHAM AWAN: He presented with no flexion of his fingers so given that it was four months out, you really have to think about what type of plan you would have and really have to be prepared for many different things intra operatively. I've seen some cases where you can get lucky and the tendons don't retract as far as you'd expect them to. If they do, then you have to be prepared to do a two stage reconstruction.
HASHAM AWAN: So in his case, we were fortunate that the tendons had retracted only to the level of the PIP joint. So the arrows show the end of the tendon here. Actually, all three fingers had retracted only to the level of the PIP joint, so we were able to do a primary repair.
HASHAM AWAN: His A2 pulleys were completely intact. We opened up the pulleys to visualize the tendon and to get it out to length and perform our repair. And here's his flex for me. I'm going to go open up all the way. Great and here's his result at six weeks post op. He had pretty remarkable. Zone 3 through 5,
HASHAM AWAN: adhesions are less likely to occur due to the lack of the fibrosis sheath. Small lacerations often involve multiple tendons because of the nerve vascular structures here, so you have to be prepared for all those. But the techniques for repairing the tendons and rehab are pretty similar to those involving Zone 1 and Zone 2. Partial lacerations have special considerations. If they're greater than 70% laceration, these should be repaired similar to complete lacerations.
HASHAM AWAN: Those between 50% and 70% can be repaired just with an epi tendinous stitch, and those less than 50% don't need to be repaired but they have a tendency to cause triggering and catching of the partial laceration on the flexor pulley so these can be debrided or simple stitches can be used to keep the tendon edge from catching on the pulleys.
HASHAM AWAN: The ultimate tensile strength is not improved by repair so again, less than 50%, you don't have to repair those, but you do worry about triggering a rupture if they are not repaired. FPL lacerations. In these, the anatomy is a little bit different so you have to be aware of the, again, the pulley system of the thumb. These also have a tendency to retract a little bit more down into the theater musculatures
HASHAM AWAN: so these may need a more extensile exposure. If the tendon stump is retracted, you can retrieve it within the carpal tunnel or more proximally, it's easier to easy to find it doing a standard distal radius approach just deep to the FCR tendon. You want to try and repair these for IP joint motion, which is important for pinch strength. Again, for these, it's important to preserve the oblique pulley, to prevent bow stringing and be prepared for these tendons to retract.
HASHAM AWAN: If they do retract or if they're chronic, you can do a primary graft with palmaris longus or an FDS tendon transfer, which is what was done in this case. And here's a tenodesis of the, see the IP joint of the thumb flexing once the wrist is extended after FDS transfer. A small incision was made at the ring finger over the proximal phalanx to harvest the FDS to the ring finger.
HASHAM AWAN: Next, we're going to talk about flexor tendon rehabilitation for Zone 2. So these are, this is very important. I tell my patients the surgery is only half the battle, the rest of it is really up to them. If they don't follow the rehab protocols, then that can lead to re-rupture or tendon adhesions, which are both difficult to deal with.
HASHAM AWAN: So there's three main rehab protocols. There's the modified Duran, there's a Kleinert, and there's an early active range of motion, which is my preference. So the modified Duran is a controlled passive finger flexion protocol. There's a dorsal orthosis which places the MCP's in flexion and slight wrist flexion. Exercises, there's passive flexion to the individual joints, active IP extension exercises, protective tenodesis and active motion begins around four weeks.
HASHAM AWAN: The Kleinert protocol uses rubber band traction to keep the fingers flexed, so it combines dorsal extension block with the rubber band traction. They start active extension exercises. 10 per hour started within the first few days after surgery. Active flexion again is delayed, usually starting at around three to six weeks after surgery. The early active protocol or Saint John protocol is what I use.
HASHAM AWAN: It requires a co operative patient and a skilled hand therapist. For the first three to five days, they remain in splint with strict elevation and immobilization. At three to five days to two weeks, they are placed in an orthosis with the wrist slightly extended MCPs at 30 degrees, IP joints extended. They start passive warmups and then work on half a full fist of active motion. The half of fist has shown to have low force but high tendon excursion.
HASHAM AWAN: You're not having them do a full fist quite yet, but you're keeping the joints supple. At two to six weeks, we switch to a short Manchester splint, which frees up the wrist and we work on synergistic motion and progressive flexion up to a full fist by six weeks. This is a great article, open access that has lots of videos so if you're interested, you can look at PRS Global Open. This is, again, the work of Don Lalonde. They have the full protocol as well as videos to guide your therapists in the rehab protocol complications.
HASHAM AWAN: So complications can happen and they're pretty common. The most common is tendon adhesions, which are higher in Zone 2 because of the flexor sheath. If the patient would require tenolisis, we try to wait at least four to six months to try and maximize the use of therapy, and then if no improvement, then you can consider tenolisis. Again, we like to try and wait as long as we can to make sure the repair is solid and you're not risking the repair by doing a tenolisis. Rupture.
HASHAM AWAN: Rupture rates vary widely, but in Jim Boateng's study of 300 patients, there was only one re-rupture. Other studies show up to 15% re-rupture rate but again, if you stick to proper surgical technique with at least a four, if not six or eight strand repair with an appartendous suture and a compliant patient with a skilled hand therapist, the re-rupture rates should be pretty low, in most series less than 5%. If there is a re-rupture,
HASHAM AWAN: it really depends on the setting and the patient factors. These may require secondary reconstruction with a graft or a Hunter rod. Other complications include joint contracture or trigger finger or Quadriga if overtightening of the repair is done. So here's a re-rupture in a compliant patient. This does warrant re-exploration and repair. If there's too much bulkiness within the sheath, you can excise the FDS, which is, again, is dependent on your surgical findings.
HASHAM AWAN: Tenolisis, flexion tenolisis sometimes needs to be done if patients have lots of flexor tendon adhesions, it's nice to do these wide awake because the patient can actively flex their fingers in the OR to determine where the adhesions are and if or when they're adequately released. You need to be prepared for pulley reconstruction and if pulley insufficiency exists, as well as if the tendon is not intact, then you have to be prepared for tendon grafting or silicone rod placement at the same time.
HASHAM AWAN: So here's an example of a patient who had three finger flexor tendon adhesions who could not flex at all at the IP joints and then the range of motion. He was motivated and worked hard with therapy and already had, he was done awake. And here is the active range of motion intraoperatively.
HASHAM AWAN: The patient can now flex at the IP joints with a near full fist. Finally, secondary reconstruction may need to be performed if there's chronicity to the injury. So reconstruction may involve a primary graft placement, which is a one stage technique or placement of a silicone rod, followed by tendon grafting
HASHAM AWAN: once the adequate sheath has been restored, usually three to four months. This is a two stage tendon grafting. Requirements for tendon grafting are supple, soft tissues. There must be good passive mobilization of the joints. It really requires a motivated and compliant patient because it requires a lot of times two operations and months and months of therapy so you have to have the right patient to be willing to undergo this procedure.
HASHAM AWAN: If you are considering a one stage graft, it must have adequate soft tissue envelope to glide through. Options for donors. There are intra synovial donors as well as extra synovial donors. So the intra synovial or the FDS or toe flexors, extra synovial donors palmaris, which is a common one, we use plantaris or toe extensors. So here's an example of one stage tenon grafting.
HASHAM AWAN: Here's a retracted FTP tendon with a gap of a couple of about 3 to 4cm and unable to get out to the...[AUDIO FADES]